Re: [Qemu-ppc] [RFC PATCH 07/10] spapr_pci: Allow PCI host bridge DMA window to be configured

[Laurent Vivier]

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On 24/09/2015 01:54, David Gibson wrote:
> On Wed, Sep 23, 2015 at 08:55:01PM +0200, Laurent Vivier wrote:
>> 
>> 
>> On 17/09/2015 15:09, David Gibson wrote:
>>> At present the PCI host bridge (PHB) for the pseries machine
>>> type has a fixed DMA window from 0..1GB (in PCI address space)
>>> which is mapped to real memory via the PAPR paravirtualized
>>> IOMMU.
>>> 
>>> For better support of VFIO devices, we're going to want to
>>> allow for different configurations of the DMA window.
>>> 
>>> Eventually we'll want to allow the guest itself to reconfigure
>>> the window via the PAPR dynamic DMA window interface, but as a
>>> preliminary this patch allows the user to reconfigure the
>>> window with new properties on the PHB device.
>>> 
>>> Signed-off-by: David Gibson <address@hidden> --- 
>>> hw/ppc/spapr_pci.c          | 7 +++++-- 
>>> include/hw/pci-host/spapr.h | 3 +-- 2 files changed, 6
>>> insertions(+), 4 deletions(-)
>>> 
>>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c index
>>> b088491..622c4ac 100644 --- a/hw/ppc/spapr_pci.c +++
>>> b/hw/ppc/spapr_pci.c @@ -1394,7 +1394,7 @@ static void
>>> spapr_phb_finish_realize(sPAPRPHBState *sphb, Error **errp) 
>>> sPAPRTCETable *tcet; uint32_t nb_table;
>>> 
>>> -    nb_table = SPAPR_PCI_DMA32_SIZE >> SPAPR_TCE_PAGE_SHIFT; +
>>> nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT; tcet =
>>> spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn, 0,
>>> SPAPR_TCE_PAGE_SHIFT, nb_table, false); if (!tcet) { @@ -1404,7
>>> +1404,7 @@ static void spapr_phb_finish_realize(sPAPRPHBState
>>> *sphb, Error **errp) }
>>> 
>>> /* Register default 32bit DMA window */ -
>>> memory_region_add_subregion(&sphb->iommu_root, 0, +
>>> memory_region_add_subregion(&sphb->iommu_root,
>>> sphb->dma_win_addr, spapr_tce_get_iommu(tcet)); }
>>> 
>>> @@ -1437,6 +1437,9 @@ static Property spapr_phb_properties[] =
>>> { SPAPR_PCI_IO_WIN_SIZE), 
>>> DEFINE_PROP_BOOL("dynamic-reconfiguration", sPAPRPHBState,
>>> dr_enabled, true), +    /* Default DMA window is 0..1GB */ +
>>> DEFINE_PROP_UINT64("dma_win_addr", sPAPRPHBState, dma_win_addr,
>>> 0), +    DEFINE_PROP_UINT64("dma_win_size", sPAPRPHBState,
>>> dma_win_size, 0x40000000), DEFINE_PROP_END_OF_LIST(), };
>> 
>> Add them too to the vmstate_spapr_pci ?
> 
> No.  At least, not just now.
> 
> This is the sort of configuration information that typically isn't 
> migrated, instead requiring the far end to be set up matching.
> Which

I think this is the aim of VMSTATE_UINT64_EQUAL() ?

> is a problem, but not one within the scope of this patch series.
> In any case just transferring the values wouldn't be enough - we'd
> need post_load handlers to actually rewire the TCE table
> accordingly.
> 
> We will need to do this once we add dynamic DMA window support,
> but again, not in scope just now.
> 
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